decision-making tools

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AA Decision-Making Tools

Decision-Making Tools

PowerPoint presentation to accompany PowerPoint presentation to accompany Heizer and Render Heizer and Render Operations Management, 10e Operations Management, 10e Principles of Operations Management, 8ePrinciples of Operations Management, 8e

PowerPoint slides by Jeff Heyl

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OutlineOutline

The Decision Process in Operations

Fundamentals of Decision Making

Decision Tables

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Outline – ContinuedOutline – Continued

Types of Decision-Making Environments Decision Making Under Uncertainty

Decision Making Under Risk

Decision Making Under Certainty

Expected Value of Perfect Information (EVPI)

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Outline – ContinuedOutline – Continued

Decision Trees A More Complex Decision Tree

Using Decision Trees in Ethical Decision Making

The Poker Decision Problem

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Learning ObjectivesLearning Objectives

When you complete this module you When you complete this module you should be able to:should be able to:

1. Create a simple decision tree

2. Build a decision table

3. Explain when to use each of the three types of decision-making environments

4. Calculate an expected monetary value (EMV)

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Learning ObjectivesLearning Objectives

When you complete this module you When you complete this module you should be able to:should be able to:

5. Compute the expected value of perfect information (EVPI)

6. Evaluate the nodes in a decision tree

7. Create a decision tree with sequential decisions

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Decision to Go All InDecision to Go All In

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The Decision Process in The Decision Process in OperationsOperations

1. Clearly define the problems and the factors that influence it

2. Develop specific and measurable objectives

3. Develop a model

4. Evaluate each alternative solution

5. Select the best alternative

6. Implement the decision and set a timetable for completion

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Fundamentals of Fundamentals of Decision MakingDecision Making

1. Terms:

a. Alternative – a course of action or strategy that may be chosen by the decision maker

b. State of nature – an occurrence or a situation over which the decision maker has little or no control

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Fundamentals of Fundamentals of Decision MakingDecision Making

2. Symbols used in a decision tree:

.a – decision node from which one of several alternatives may be selected

.b – a state-of-nature node out of which one state of nature will occur

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Decision Tree ExampleDecision Tree Example

Favorable market

Unfavorable market

Favorable market

Unfavorable market

Construct small plant

Do nothing

A decision node A state of nature node

Construct

large plant

Figure A.1

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Decision Table ExampleDecision Table Example

Table A.1

State of Nature

Alternatives Favorable Market Unfavorable Market

Construct large plant $200,000 –$180,000

Construct small plant $100,000 –$ 20,000

Do nothing $ 0 $ 0

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Decision-Making Decision-Making EnvironmentsEnvironments

Decision making under uncertainty Complete uncertainty as to which

state of nature may occur

Decision making under risk Several states of nature may occur

Each has a probability of occurring

Decision making under certainty State of nature is known

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UncertaintyUncertainty

1. Maximax Find the alternative that maximizes

the maximum outcome for every alternative

Pick the outcome with the maximum number

Highest possible gain

This is viewed as an optimistic approach

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UncertaintyUncertainty

2. Maximin Find the alternative that maximizes

the minimum outcome for every alternative

Pick the outcome with the minimum number

Least possible loss

This is viewed as a pessimistic approach

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UncertaintyUncertainty

3. Equally likely Find the alternative with the highest

average outcome

Pick the outcome with the maximum number

Assumes each state of nature is equally likely to occur

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Uncertainty ExampleUncertainty Example

1. Maximax choice is to construct a large plant2. Maximin choice is to do nothing3. Equally likely choice is to construct a small plant

Maximax Maximin Equally likely

States of Nature

Favorable Unfavorable Maximum Minimum RowAlternatives Market Market in Row in Row Average

Construct large plant $200,000 -$180,000 $200,000 -$180,000 $10,000

Constructsmall plant $100,000 -$20,000 $100,000 -$20,000 $40,000

Do nothing $0 $0 $0 $0 $0

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RiskRisk

Each possible state of nature has an assumed probability

States of nature are mutually exclusive

Probabilities must sum to 1

Determine the expected monetary value (EMV) for each alternative

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Expected Monetary ValueExpected Monetary Value

EMV (Alternative i) = (Payoff of 1st state of nature) x (Probability of 1st state of nature)

+ (Payoff of 2nd state of nature) x (Probability of 2nd state of nature)

+…+ (Payoff of last state of nature) x (Probability of last state of nature)

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EMV ExampleEMV Example

1. EMV(A1) = (.5)($200,000) + (.5)(-$180,000) = $10,000

2. EMV(A2) = (.5)($100,000) + (.5)(-$20,000) = $40,000

3. EMV(A3) = (.5)($0) + (.5)($0) = $0

Table A.3

States of Nature

Favorable Unfavorable Alternatives Market Market

Construct large plant (A1) $200,000 -$180,000

Construct small plant (A2) $100,000 -$20,000

Do nothing (A3) $0 $0

Probabilities .50 .50

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EMV ExampleEMV Example

1. EMV(A1) = (.5)($200,000) + (.5)(-$180,000) = $10,000

2. EMV(A2) = (.5)($100,000) + (.5)(-$20,000) = $40,000

3. EMV(A3) = (.5)($0) + (.5)($0) = $0 Best Option

Table A.3

States of Nature

Favorable Unfavorable Alternatives Market Market

Construct large plant (A1) $200,000 -$180,000

Construct small plant (A2) $100,000 -$20,000

Do nothing (A3) $0 $0

Probabilities .50 .50

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CertaintyCertainty

Is the cost of perfect information worth it?

Determine the expected value of perfect information (EVPI)

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Expected Value of Expected Value of Perfect InformationPerfect Information

EVPI is the difference between the payoff under certainty and the payoff under risk

EVPI = –Expected value

with perfect information

Maximum EMV

Expected value with perfect information (EVwPI)

= (Best outcome or consequence for 1st state of nature) x (Probability of 1st state of nature)

+ Best outcome for 2nd state of nature)

x (Probability of 2nd state of nature)

+ … + Best outcome for last state of nature)

x (Probability of last state of nature)

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EVPI ExampleEVPI Example

1. The best outcome for the state of nature “favorable market” is “build a large facility” with a payoff of $200,000. The best outcome for “unfavorable” is “do nothing” with a payoff of $0.

Expected value with perfect information

= ($200,000)(.50) + ($0)(.50) = $100,000

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EVPI ExampleEVPI Example

2. The maximum EMV is $40,000, which is the expected outcome without perfect information. Thus:

= $100,000 – $40,000 = $60,000

EVPI = EVwPI – Maximum EMV

The most the company should pay for perfect information is $60,000

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Decision TreesDecision Trees

Information in decision tables can be displayed as decision trees

A decision tree is a graphic display of the decision process that indicates decision alternatives, states of nature and their respective probabilities, and payoffs for each combination of decision alternative and state of nature

Appropriate for showing sequential decisions

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Decision TreesDecision Trees

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Decision TreesDecision Trees1. Define the problem

2. Structure or draw the decision tree

3. Assign probabilities to the states of nature

4. Estimate payoffs for each possible combination of decision alternatives and states of nature

5. Solve the problem by working backward through the tree computing the EMV for each state-of-nature node

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Decision Tree ExampleDecision Tree Example

= (.5)($200,000) + (.5)(-$180,000)EMV for node 1= $10,000

EMV for node 2= $40,000 = (.5)($100,000) + (.5)(-$20,000)

Payoffs

$200,000

-$180,000

$100,000

-$20,000

$0

Construct la

rge plant

Construct small plant

Do nothing

Favorable market (.5)

Unfavorable market (.5)1

Favorable market (.5)

Unfavorable market (.5)2

Figure A.2

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Complex Complex Decision Decision

Tree Tree ExampleExample

Figure A.3

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Complex ExampleComplex Example

1. Given favorable survey results

EMV(2) = (.78)($190,000) + (.22)(-$190,000) = $106,400EMV(3) = (.78)($90,000) + (.22)(-$30,000) = $63,600

The EMV for no plant = -$10,000 so, if the survey results are favorable, build the large plant

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Complex ExampleComplex Example

2. Given negative survey results

EMV(4) = (.27)($190,000) + (.73)(-$190,000) = -$87,400EMV(5) = (.27)($90,000) + (.73)(-$30,000) = $2,400

The EMV for no plant = -$10,000 so, if the survey results are negative, build the small plant

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Complex ExampleComplex Example

3. Compute the expected value of the market survey

EMV(1) = (.45)($106,400) + (.55)($2,400) = $49,200

The EMV for no plant = $0 so, given no survey, build the small plant

4. If the market survey is not conducted

EMV(6) = (.5)($200,000) + (.5)(-$180,000) = $10,000EMV(7) = (.5)($100,000) + (.5)(-$20,000) = $40,000

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Decision Trees in Ethical Decision Trees in Ethical Decision MakingDecision Making

Maximize shareholder value and behave ethically

Technique can be applied to any action a company contemplates

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Yes

No

Yes

No

Decision Trees in Ethical Decision Trees in Ethical Decision MakingDecision Making

Yes

Is it ethical? (Weigh the affect on employees, customers, suppliers,

community verses shareholder benefit)

NoIs it ethical not to take

action? (Weigh the harm to shareholders

verses benefits to other stakeholders)No

Yes

Does action maximize company returns?

Is action legal?

Figure A.4

Do it

Don’t do it

Don’t do it

Do it, but notify appropriate parties

Don’t do it

Action outcome

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The Poker Design ProcessThe Poker Design Process

If T. J. folds,

If T. J. calls,

EMV = (.80)($99,000)

= $79,200

EMV = .20[(.45)($853,000) - Phillips’ bet of $422,000]

= .20[$383,850 - $422,000]

= .20[-$38,150] = -$7,630

Overall EMV = $79,200 - $7,630 = $71,750

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